Thanks for the replies, but after testing my extension tubes out, I feel they are GREAT value for money!!!
Aperture:
It didn't bother me too much, I simply preset the aperture, sure it was harder to adjust focus using it stopped down to f32 (was just testing it.)
but i took a few images and finally (after about 4 -5 images.) got focus fine.
metering:
My canon seemed to meter the scene perfectly, I made sure the little line was under 0 and everytime, the exposure come out perfectly.
focusing:
I have a 75-300mm with broken AF (bought like that.) so used manual focus a lot on that, it doesn't bother me too much, I have also found that it helps and gives better results if you twist the focus to the furthest distance (twist to the right.) seems to be better, then just move forward and backward to correct focus.
Lenses used to test extension tubes:
85mm usm 1.8
75-300mm usm on 75mm and at 300mm!!
the 85 mm got really close and personal to the object (little less than 12 inches away.) for it to be sharp.
the 300mm was about 1 metre away to be sharp and still looked macro - possibly my favourite as it means, with a quick enough shutter speed, it would be great for capturing small bugs!
the 75 mm was about 6 inches away to focus correctly.
I did not actually take a photograph with the 75-300mm as i had packed away my tripod by that time (I went with the giottos fyi, which I wish i went with manfrotto now
the giottos is just too flimsy feeling compared to the manfrotto - it does have a little more functuality to it though.)
but the optical quality from the 85mm is great, much better than my macro filters, I would go as far to say, better than the sigma lens in my college achieves! (105mm macro.)
therefore if the only advantages really from more expensive (with the exception to using heavy lenses!!!!) extensions, I don't mind saving £110 as I prefer to do things manually, makes me feel more involved / in charge rather than allowing the camera to do everything.
but I do agree, I would not use a heavy lens on them, they do feel fairly stable but wouldn't want to risk it just incase.
They are made of aluminium I think, they are definately metal.
they have no screws, it uses threads at the ends (like filters.)
The only thing that does dissappoint me with them is:
they don't have a lens release button.
all you do is twist to the right and pull off instead of pushing the button then doing that, sure it is quicker but it can make it come of when un wanted (not exerienced that yet.)
but what I have experienced was; when I first tried to take the lens off - it seemed like it had stuck, a few little nudges fixed it, it happened again later but fixed easily again.
I don't think you can go wrong with extension tubes, as long as it is light tight.
I would definately recommend them tbh.
I would consider the Opteka Extension tubes if I was seeking Auto modes.
I will try post up some images from it soon!
